The introduction of the central London congestion charge has apparently emptied the capital's shops as well as its roads.
Shopper traffic monitor FootFall reported fewer shoppers in the West End on Monday and Tuesday, the first two days of charging.
According to FootFall, the number of shoppers was down 12.4 per cent on the same Monday last year, and down 12.5 per cent on Tuesday.
But week-on-week figures showed an increase of 4.7 per cent compared with last Monday and 7.1 per cent for Tuesday.
Marketing manager David Smyth said charging has deterred shoppers from driving into London.
'The week-on-week figure has shown an increase, but this was not the level of increase that would be expected, as the year-on-year figures show.'
Retailers were reluctant to comment on the charge's impact. A House of Fraser spokeswoman said it is too early to draw accurate conclusions.
However, the department store group intends to 'add value' via special promotions.
A Debenhams spokeswoman said: 'Our Oxford Street store is holding up well.'
Selfridges declined to comment, because it is in a closed period. The retailer does, however, intend to install self-service payment machines in the store and car park.
Marketing director James Bidwell said: 'The congestion charge is a fact of life, it's happening. We are putting in four pay-points, enabling customers to pay if they have forgotten and generally making life easier for them.'
Bidwell admitted that although driving is a popular way of getting to Selfridges, drivers are a small proportion of its 30,000 daily visitors.